TommyDS v3.0

• Added support for 64-bit platforms and 64-bit integers. When building on
  a 64-bit platform you can store more than $2^{32}$ objects in the containers.
  This doesn't apply to tries that are able to store only 32-bit integers,
  but you can change this with the TOMMY_TRIE_BIT and TOMMY_TRIE_INPLACE_BIT
  definitions.
• Fixed undefined behavior in hashing functions. It could cause issues
  with vector instructions.
• Reorganized some structures to avoid padding.
• Removed the tommy_count_t type that is now always replaced by tommy_size_t.
• Renamed the "key" field of the tommy_node_t to "index" to be more generic
  on the possible use.
• Added TOMMY_API to override linkage features of the interface. Useful for
  amalgamations [Nodir Temirkhodjaev].